More and more mobile terminals now come with an NFC (Near Field Communication) reader/writer functionality and are capable of peer-to-peer communication with other terminals. Some mobile terminals incorporating reader/writer functionality are intermittently outputting a carrier wave (packets) to attempt to find a terminal to communicate with through NFC. Many of such mobile terminals have a function that allows a user to reading information from another terminal simply by bringing the mobile terminal close to that correspondent terminal without needing a user operation on the terminal. The NFC reader/writer function can be abused at an office or on a crowded train to read information from the user's mobile terminal when the mobile terminal is put aside.
Of course, information that a mobile terminal incorporating reader/writer functionality can read is information that does not require authentication. Many mobile terminal users, however, regard such readable information as being private information that the users do not want to reveal to others. In the case of fare cards for transportation services (such as suica (registered trademark)), for example, information such as (1) history information about stations used and time and date of use, (2) history information about ticket gates passed through, and (3) the prepaid balance information on the card can be read without needing authentication. Allowing these kinds of information which can be read without needing authentication to be read without restriction through a mobile terminal incorporating reader/writer functionality poses many problems in terms of personal information protection.
A mobile terminal incorporating near-field IC card functionality disclosed in Patent literature 1 is intended to prevent external unauthorized access to the mobile terminal by a person other than the owner of the mobile terminal when the mobile terminal is not in use. When the mobile terminal with near-field IC card functionality in Patent literature 1 detects a radio access signal to the near-field IC card part, the mobile terminal accepts the external access if a tilt sensed by a tilt sensor is within a predetermined tilt range; otherwise disables the near-field IC card part functionality. The near-field IC card part is used normally while being held horizontal to or near horizontal to the ground. Control means of the mobile terminal with near-field IC card functionality in Patent literature 1 therefore does not immediately enable the near-field IC card part when the control means detects a radio access signal to the near-field IC card part, but makes a determination as to the tilt of the terminal detected by tilt sensing means. If the detected tilt of the terminal is not within a predetermined range, for example if the terminal is placed in a pocket of the user's clothing vertically or near vertically, the control means determines that the attitude of the terminal does not indicate an expected situation in which the terminal is used by the user and disables the near-field IC card part. This can prevent external unauthorized access to the near-field IC card part.